3 component laboratory experiments by laser interferometry: anisotropy estimations using polarization of quasi P-waves and S waves

Transcription

1 3 component laboratory experiments by laser interferometry: anisotropy estimations using polarization of quasi P-waves and S waves Maxim Lebedev, Andrej Bóna, Roman Pevzner, Boris Gurevich Department of Exploration Geophysics, Perth, Australia

2 Linking Laboratory, Computational and Field Experience OUTLINE Motivation: why knowledge of anisotropy is important Anisotropy: what we do in the lab Anisotropy: new approach in the field Anisotropy: bring this approach to the lab Laser Doppler Interferometry Validation experiments Conclusion

3 Why knowledge of anisotropy is Standard US image important? Seismic image: oil reservoir

4 How anisotropy is determined at laboratories: basic principles 1. traveltime 2. travel path 3. velocities Slowness Density }inversion waves receiver waves

5 How anisotropy is determined at laboratories: complicate experimental systems

6 How anisotropy is determined at laboratories: clear or unclear data interpretation A B A What is the travelpath B? C C

7 How anisotropy is determined at laboratories: expensive rigs Institute of Geology, Prague, Czech Republic Courtesy of Dr. Miroslav Brajanovski

8 Anisotropy: new approach in the field The inversion approach stiffness tensor slowness density polarization System of three linear equations in c for each measurement Solution by Total Least Squares Uses P and S waves Assumes lateral homogeneity [Dewangan & Grechka, 2003]

9 P wave: horizontal slowness and polarization from Otway basin (Australia) 3D/3C VSP 3C geophone depth 1590 m Data acquired by CO2CRC

10 Inverted density scaled stiffness tensor stiffness tensor slowness density polarization

11 Z Field:3C geophone X Y

12 E.I. Galperin 1984: The Polarization Method of Seismic Exploration Z X Y Z3

13 It will be nice if, Size of receivers will be small Complementary measurements of Waves polarizations

14 Measurements of wave polarisation in laboratories

15

16 Bayon, A., Rasolofosaon, P. N. J., 1996, Three-component recording of ultrasonic transient vibration by optical heterodyne interferometry, The Journal of the Acoustical Society of America

17 Laser Doppler Interferometer 1C sample Laser Bragg Cell Photo Detector

18 3 C laser interferometers are available on market, but

19 Velocity Displacement Vertical displacement, nm m mm mm

20 S wave measurements using interferometer? It is possible Measurement 1 Measurement 2 α α S wave = ½(Measurement1 x cos (α) Measurement 2 x cos (α))

21 Reflective tape 50-µm-diameter glass beads 1 mm

22 Optimization of the direction of measurement (laser beam incident angle) Measurement β displacement = Measurement /sin (β) Angle, 90-β

23 3C at the lab Z Particle Velocity Vector axis 3 35º axis 1 35º 120º 120º axis 2 35º X Y

24 Z axis 3 35º axis 1 35º 120º 120º axis 2 35º X Y Rock Physics laboratory at Curtin University, Perth, Western Australia

25 Test experiment 1: S wave splitting S V

26 C Tested media paper reinforced phenolic Vp 3519m/s Vp 2875m/s A B Pulse S V C Z X Y 1 mm

27 SV and SH measurements at 3C configuration Z Y X x x x 10-5 Time, s x10-5 Z, Z, m x10-8 x x Sv Sh x 10-8 S V Z Y, m X, m X Y

28 Test experiment 1 (b) Comparison: Interferometer vs Transducer: Same source (S-transducer) and Measurements at the SAME directions interferometer S transducer V V V H H H

29 Test experiment 2: artificial TI media X Z Pulse Source 0.5 MHz paper reinforced phenolic Vp 3519 m/s Vp 2875 m/s

30 Polarization of q-p wave: Experimental result S wave arrival (based on polarisation) X Z X Y Z x x x 10-5 P wave arrival (based on polarisation) time

31 Polarization of q-p wave: Experimental result Z x 10-9 X 3 2 Z, nm Y, m x 1

32 Polarization of q-p wave: Experimental result Z X Z, nm Z, m 0-1 Z, Z, nm m Y, nm X, nm

33 Polarization of q-p wave: Forward modelling paper reinforced phenolic : Stiffness tensor 7 0

34 Test experiment 3: walk away artificial TI media Z X paper reinforced phenolic Vp 3519 m/s Vp 2875 m/s Pulse Source 0.5 MHz

35

36 paper reinforced phenolic: 3C common shot gather X Y Z P T, µs S V S H

37 Polarization of q-p wave: Forward modelling paper reinforced phenolic : Stiffness tensor C = GPa, ray Thomsen parameters are γ=0.08, δ=0.25, ε=0.23, and α=2887m/s, β=1548m/s.

38

39 Linking Laboratory, Computational and Field Experience Conclusions (not final!) 3 component velocity field method has been transferred to laboratory A method for estimation of anisotropy of rock samples based on the laboratories measurements of the velocities and polarizations of elastic waves has been proposed More theoretical analysis of the wave behavior at interfaces is necessary to fully unlock the potential of the presented method for stiffness tensor estimation. Next step in this study: Measurements of anisotropy under triaxial stress

40

41

42 Footer text - slideshow title

43

44 ?

45 Linking Laboratory, Computational and Field Experience Figure from the book Les Tremblements de terre (Earthquakes) by Ferdinand André Fouqué 1889

46 Linking Laboratory, Computational and Field Experience from countries and continents

47 Thank you!

48 Elastic anisotropy determination Apparatus Measurements X Y Z x x x 10-5 Apparatus for elastic anisotropy determination at the Rock Physics Laboratory, Department of Exploration Geophysics, Curtin University of Technology Algorithm elastic properties (anisotropy)